Amylase activity during baking - serious doubts

that produces a really wonderful bread: both sour and tasty AND in a very limited cooking time - at least limited when compared to the typical times of rye breads. I mean that in ~90 minutes the bread is perfectly cooked, sweet and chocolate brown. The only reason why I don't do this bread more often is that it takes 3 days of fermentation.

In the meantime reading many threads in TFL I got convinced that baking a rye bread at an initial very high temperature (even 260-300°C if possible) for 10 minutes serves the purpose of disabling the amylase activity to stabilize the crust and the crumb and prevent collapsing of the dough.

There's something that doesn't convince me. Given that

-the temperature of the bread typically reaches 93°C after a lot of time, 45-50 minutes of baking at high temperature

-the alpha-amylase reaches a peak of activity at 65°C, continuing somewhat up to 75° and stops completely above that temperature

how is it possible that after only 10 minutes at 260°C the internal temperature of the dough is already above 65°C, or even 75°C?

I tend to guess that -at the opposite of what I believed so far- the very high temperature of the oven at the beginning takes the dough to a temperature very near 65°C, maximizing the activity of alpha-amylase and releasing more sugars in the dough (this would explain why the bread in the recipe I linked comes out always so dark and sweet).

Moreover, I verified that cooking the exact same recipe at lower temperatures doesn't result in an equally dark and sweet bread, thus the effect of the massive amount of gelatinized soaker (36%) seems to have a secondary importance than the baking methodology.

Maybe only the outermost part (the crust) reaches a temperature above 75°C in little time and works as a support for the rest of the dough?

I'am sure you read in Hamelman's Bread that Bakers in Germany insert their proofed Ryes in special ovens that shoot for an initial heat of 600F for 5 to 8 minutes in order t get the maximum oven spring, then loaves are transferred to regular ovens with reduced temperature for the rest of baking time.

I've had a good look through the recipe posted in the link, and I've also read through the relevant pages of Jeffrey Hamelman's book. These are pp.23-25 for an in-depth discussion of the baking process, pp.45-49 for a discussion of rye flour and pp.191-192 for steaming and baking of specifically rye breads. There is an excellent discussion in these pages. You are probably already aware that I consider Jeffrey Hamelman to be one of the very best bakers practising today; his book does not have a modern-day rival, although Suas recent work is very much up there. The best aspects of this book are twofold: one, all the recipes work; two, the author makes an unparalleled contribution to opening up rye bread baking to a mass Western audience. Maybe I should say "English-speaking" to be more accurate, but I'm not sure if that's correct, or not?

I can also bring my own commercial experience to bear by comparing the loaf you discuss with the Rossisky bread we made during my time at Village Bakery.

I will try to cover the ground, but there is a lot to get through. If I've missed anything out just let me know.

Let's do a side by side comparison. Weston A. Price Rye Sourdough weighs 1500g, has [approx] 78% hydration and is in the oven for 66 mins [correct me if I'm wrong here Nico, you said 90 mins?] VB Rossisky was scaled at 960g, had 85% hydration, and baked for 50 minutes at 210*C in a wood-fired RACK oven! I have to be honest from the outset, I know nothing whatsoever about Dutch ovens! So, please forgive me if any errors pertain.

Mebake, you rightly say Hamelman discusses the high initial heat as a means to engineer oven spring. Here we are talking about ovens constructed from a huge mass of masonry, where significant heat is retained in the sole of the oven; this is an extremely important concept. I'm not sure it applies to domestic oven. A pizza stone will be of limited effect, even the bricks I have in my own oven will not be that effective. We are talking about several tonnes of masonry here. Otherwise the fierce heat will be too much directed from freshly injected thermostatic heat, working primarily at the top of the loaf. This is of no use, as the top of the loaf will scorch, and there will not be sufficient heat directly underneath the bread to encourage the spring being discussed. Originally VB Rossisky were baked in the 35 tray wood-fired French brick oven, and were extremely effective at taking up some of the excess heat from the newly-fired oven. The large loaves had to go at the back of the oven, where the top heat was not so fierce. The bake time was a minimum of 45 minutes. I think the rack oven did a better job of baking this bread [a very rare compliment, as I generally detest this type of oven!]. The door seal on these ovens is fantastic, and the supply of steam is unsurpassed. If you have read my posts on Horst Bandel's Black Pumpernickel, you will know that I like to use a large element of steam to cook rye bread. ACTUALLY, I rather think this has a significant bearing on enzymatic activity and forming that very dark and sweet loaf Nico is looking for. The thing is that use of steam produces a softer crust. Try as I might with Hamelman's technique of baking on the dead oven, I have failed completely in the home environment. Baking in coffins utilising a steam bath in the wood fired oven produces superb loaves, cooked overnight, just as Jeffrey Hamelman advocates. But I cannot translate that to making large loaves in the oven at home...one day, maybe? Best news so far, is that I made HB loaf in a Pullman Pan in College last week using the Combi Oven and steaming for 8 hours: magnificent, and will try to post on that soon. See here for my posts on HB: http://www.thefreshloaf.com/node/17931/horst-bandel039s-black-pumpernickel and http://www.thefreshloaf.com/node/17254/horst-bandel039s-balck-pumpernickel

So far, I'm not sure about this sudden blast of heat being SO significant in raising the internal temperature of the baking bread. Here's why: we are talking about BIG loaves [960g VB, and 1500g Weston] and high hydration. The high water will obviously help to raise the dough temperature quite quickly, but we are talking about a relatively dense loaf, and a significant amount of water to drive off in order to achieve a successful bake.

What I'm slowly coming to Nico, is the temperature path you record. For the VB loaf, indeed, we would look for 95*C after the 50 minute mark. I would assume the Weston loaf would record a similar temperature at 66 minutes with the profile offered using the Dutch Oven.

Well, we did exactly this trial when I studied for my Bakery quals back in 2004 at Leeds, BUT, not with Rye Sourdough breads. It may still be instructive for me to run through the trial. We baked white tin loaves, scaled at 470g, with hydration of 63%, taking samples out of the oven at various intervals to record temperature details etc. The prover ran at 35*C, so that would be the dough temperature when we put the bread into a deck oven running at 235*C. It took a full 8 minutes for the core temperature to exceed the magic 53*C figure which is the point when yeast activity ceases. I still have the graph charting all the information, but it is at College, and it's now 10pm and I'm happily at home; so this is from memory, but with confidence I'm correct. The dough temperature at the core of the baking loaf actually takes a relatively slow trajectory to begin with to reach 65*C after 15 minutes and just short of 19 minutes to reach 80*C. We hit 95*C after 23 minutes.

I think this shows the rye doughs are unlikely to meet the temperasture and time targets you envisage Nico. But they are not a million miles away, given the high water content will aid more rapid temperature rise. HOWEVER, the big factor with baking to me is always to bake as hot as possible, always ensuring the product is in the oven long enough to complete the cycle, but to complete that cycle in the shortest possible time. This should ensure only the minimum amount of water is driven off necessary to bake the loaf!

I'm not sure the high initial heat is aiming to kill off enzymatic activity as quickly as possible. Let me quote from the book:

Mebake is exactly right that Hamelman is looking to create good oven spring at a point where a wet and weak dough structure is actually very vulnerable. I do, however, take the point that enzymatic activity does continue, and will only cease AFTER rye starch gelatinisation is fully complete. It is important to note that rye starch gelatinises at a lower temperature than wheat. Hamelman goes on to explain the dangers of "starch attack" on pp.47. Here he notes that continued amylase activity means starches are still being converted to sugar as the starches are gelatinising. Too high a proportion of sugar in the baking dough at this stage is a major issue and will result in gummy dextrins and product failure. The important tool to prevent over active amylase is....SOURDOUGH!

Actually, Nico, I think the zavarka is significant in obtaining darkness and sweetness. It was part of the originall VB concept in creating the sourdough. The rye flour was indeed gelatinised first, then cooled, before adding back stock rye sourdough to ferment the next batch. From experience, I remember hating having to carry huge vats of boiling water around the bakery in order to complete these tasks. It's all very well using a kettleful in your own kitchen at home, but we are talking about 35L of boiling water here!!!

Maybe this is of help? Thanks for raising such an interesting and complex question.

First a clarification: in the Weston recipe the baking time is longer than 66minutes, because the bread is baked starting from a cold oven and it takes a while to get to 500°F/260°C (in my case approximately 20 minutes, depending on which oven I use). I never baked this bread in a dutch oven bacause my cast iron pot is far too big for the amounts of bread I bake for myself, thus I always had to use aluminum forms (maybe a pyrex glass would be a better approximation of a dutch oven).

I didn't imagine that a very wet dough (like most rye doughs) would reach a high temperature more efficiently than a less wet dough; I was rather convinced of the opposite. This fact alone already overthrows my initial assumptions.

Your quote from Hamelman's book indeed doesn't mention anything related to enzymatic activity; that idea I gathered reading various thread in TFL.

There's another thing that makes me understand what tortures I regularly submit my breads to: you wrote it's better baking at 210°C in an oven as hot as possible in the shortest possible time, while I regularly did the opposite, even when not aiming at a pumpernickel-style baking (very long and very slow).

Well, it's evident I have to radically change my baking habit! Let's see the results at the next baking.

Talk to Mini about long slow baking. I know nothing whatsoever about it, and that's why I didn't work out your 90 minute schedule.

I don't think slow baking is wrong, far from it! It's just that it works in a way completely contrary to the commercial methods I have been taught and adopted.

I'm sure that baking from cold has its advantages, which will be different from the ones I have outlined for my preferred oven techniqiues. But try to see it from my point of view here: commercially we want as much shelf life as possible, especially given I don't cheat and add fancy additives and the like. So retaining as much moisture in the baked product as possible becomes key. It stands to reason that the quicker a product is baked, the less it will dry out. That is why I am so averse to the twice-baked products which manufacturers like to describe [wrongly] as "par-baked". The great thing about rye is that the dough is highly hydrated anyway, so there is better moisture retention.

And I love the long slow concept for Pumpernickel too; but I think a constant supply of steam in the oven [or steaming pan, often, in my case] is crucial to keeping the loaf moist. I really don't like a hard crust on rye bread, however dark it finishes up. What's your take on that?

My reasoning for thinking a wet dough will heat up quicker is that water will conduct heat better than flour. Please do correct me if I'm wrong here; my understanding of Physics is absolutely awful; I couldn't even pass my "O" Level in the subject!!!

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